This invention relates to the process now known as TCET (transcranial electrotherapy), that is to say the application of a series of electric signals of defined amplitude and duration across the head of a patient or a test animal by means of percutaneous electrodes generally attached to the external part of the ear.
TCET is described in detail in U.S. Pat. No. 4 646 744 issued Mar. 3, 1987. The U.S. patent describes the general concept of TCET and distinguishes it from other known methods, in particular TENS (Trans cutaneous Electrical Nerve Stimulation), electro-acupunture and invasive electrical treatment. TCET is particularly important in the control of chronic refractory pain, but is also important in treatment of addictive states.
We have now found that for TCET to be successful a number of factors must be considered and the application of the electrical signals must be carried out in a precisely defined manner using signals having particular parameters. It is thus the object of the present invention to provide a method of applying TCET which is effective and reproducible.
U.S. Pat. No. 4 646 744 discloses the application of a signal comprising trains of pulses separated from other trains by off periods. Each of these trains comprises a packet of a certain number of individual pulses spaced temporally from other packets by off periods. The pulses are generally either DC or substantially symmetrical AC wave forms applied at a number of different frequencies, typically 10 Hz, 100 Hz, 25-30 Hz, 500 Hz, and 200 Hz. The pulse width, that is to say the duration of a positive pulse from a zero value to a zero value, is typically 0.1 to 0.5 msec, although pulse widths of 1.5 msec are also mentioned. As described, the signals have a current of several mA, and an amperage of less than 100 mA being sufficient.
As stated, the pulses are given in packets of consecutive pulses described as "trains" separated by off periods which can regularly spaced or which can be irregular and typically increasing in duration, e.g. in an arithmetical progression. The typical overall duration of these series of trains is several days.